Components in addition to active electronic devices must be mounted on printed circuit boards. For example, electrical connectors must be mounted on either through hole or surface mount printed circuit boards to permit interconnection of other printed circuit boards or electrical cables. Although these components will be attached to the printed circuit board by virtue of the solder connections, additional mechanical connection is desirable. First, some means of attaching the device to the printed circuit board prior to soldering the leads to the printed circuit board is needed. Perhaps more importantly, mechanical attachment of the components to the printed circuit board is needed to prevent damage to the solder joint as a result of mechanical forces and loads applied to the component.
One common means of mechanically attaching a component, such as an electrical connector to a printed circuit board is to use mounting screws to attach the component. This approach, however requires the use of additional components including screws, nuts and washers. These additional components not only add packaging and inventorying complications, but perhaps more importantly, add additional assembly operations with a resulting increase in the applied or total cost of the product.
An alternative method of attaching components, such as electrical connectors, to printed circuit board is to use special metal fasteners. These fasteners can be initially mounted in the electrical connector to minimize handling problems, or they can be inserted at the time the component is assembled to the printed circuit board. One example of fasteners of this type is shown in U.S. Pat. No. 5,295,862. Although these metal fasteners may be easier to assemble than screws, they still represent added components and added cost.
Another common approach to attaching components, such as electrical connectors, to printed circuit boards is to use mounting fasteners or holddowns which are integrally molded as part of the component housing. These molded fasteners are usually inserted into holes on printed circuit boards and generally employ a downwardly facing inclined or beveled lead-in surface. These fasteners can be deflected upon insertion into a hold and will snap back so that an upwardly facing perpendicular latching surface engages the board after complete insertion. Examples of such snap latch fasteners are shown in U.S. Pat. Nos. 4,080,522; 4,139,727; and 5,178,554.
A similar conventional molded mounting fastener is a split mounting post. These mounting posts are generally cylindrical with a slot separating the post into two resilient cantilever beams. Inclined lead in surfaces and perpendicular latching surfaces are normally located at the distal end of these split beam posts. These lead-ins and latching surfaces can be employed on both posts, but the molds must either provide clearance for molding these latching surfaces or incorporate side pulls into the molds, or require that overhanging lips on these latching features deflect to snap out of the mold. In some cases, only one of the posts will include lead-in and latching surfaces on the ends of the posts. One example of a split beam mounting post is shown in U.S. Pat. No. 5,112,235.